Try installing your theme again, taking care to upload your theme folder to:
Once uploaded, you should see in your FTP screen this:
Before uploading, double check that the theme folder has only one folder and not two folders.
When you click open the theme folder on your desktop, do you immediately see all the files and stylesheets within? Or do you have to open yet another folder before you see the files?
If you have to open another folder, then you are uploading the theme with double folders, and one HAS to go otherwise the stylesheet will not be referenced properly.
Once you've uploaded a single folder theme to your wp-content/themes click your FTP refresh button, then go to your wordpress dashboard and click refresh in your browser toolbar.
Once refreshed, check: Admin/Presentation/Themes
It should be there.
PS: It helps to CHMOD your theme files. Files are generally set to 666. Making them writable will allow you to tweak the templates in your dashboard under: Dashboard/Presentation/Theme Editor if you need to.
When you're satisfied that all is grand, use your FTP again and change the permissions on your files back to 644 & theme folders to 755 to protect them.
Hope this helps.